"Ah, I remember this; it was the only place in the city you could get a proper wooden clothes pole," grins Britain's most affably bankable literary talent, or at least the one most devoid of airs, graces or hints of pretension. You get the feeling he'd happily have settled for a pork pie and can of Irn-Bru on some nearby castle steps but for the fact that a) I wouldn't, and b) Ian Rankin increasingly does like his good food.

And so we're in Timberyard, just the latest go-to venue in a series of winning conversions throughout Edinburgh with high-end food, a glass or two, and enough vaulting space to nullify clatter while still warming to the echoes of Edinburgh folk. The former Lawson's Timber store/shop has sawdusty memories for many – of clothes poles, of the fat £2 sacks of offcuts, of the storemen with quiet brown moustaches and old school ties knotted thinly under brown overalls. It's just beginning to create new memories today. At the end, as candles are being lit against encroaching dusk, my guest says he'll definitely be coming back, of an evening, with his wife.

"The nice thing about Edinburgh is that despite the recession there always seems to be a good new restaurant opening. We know now about Martin Wishart, the Plumed Horse, and Kitchin just seems to go from strength to strength, but there always still seems to be somewhere new, like this. My agent or publisher will come off the plane, they're used to London, and I take them to these places and they can't believe how good, and how cheap they are. I really like this one today so far – though does it seem a bit London to you? A bit Clerkenwell?" I see what he means, but only a Scottish city could let you luxuriate in this amount of space at non-mad prices. We have finally settled on the menu, after much humming and ha-ing in which he helpfully reads out specials from the (proper huge old school trundling-roller) blackboard behind me while I keep lazily asking "what was the middle thing again?" His dark eyes shine a little at the beef tongue and kale: "I've not had tongue since I was a wee kid – let's see what it's like."

As, now, an extraordinarily bestselling author – his thrillers, particularly the Rebus series, have been translated into more languages than there are languages – he can't be a stranger, surely, to memorable foreign meals. "Yes and no. Often I'd rather just go back and order a steak from room service, cos I'm up at 6am for a flight. What I do like to do when I hit a strange place is often just hit the bars, you get the best early feel for a place, and you often get food. Though I try not to go anywhere with a bouncer on the door; not a bad rule for much of life. And now there's Twitter! I can go on and say, hey, I'm going to Ottawa, anywhere good to drink there? And actually there was, old-fashioned wood, burgers, music, real ale."

Ah, ale. Which brings us to Rebus, ostensibly the reason for meeting. Rankin retired him a few years ago – he says he "didn't have the heart to actually kill him off; never would" – and wrote a couple of splendidly received books about Rebus's polar opposite, the taciturn, teetotal internal affairs cop Malcolm Fox. But Rebus, as part of a burgeoning new "cold-cases" section for sharp, scarred Scottish ex-cops, lives again this month, even more bitter, unorthodox – and ambiguously triumphant – than before.

"Yes, John Rebus: a man who doesn't eat out very often," smiles his creator. "They've even stopped doing his rolls in the Oxford Bar [in real life]. Yes, it's good to have him back. Nobody suggested I bring Rebus back. In fact my wife said don't. Rebus's head's not an easy place to be, and when I'm researching and writing him I'm probably not a great person to be with. But I wanted him back. And no, I didn't have any worries with setting him in this against Malcolm Fox. It was organic. Here's a character I spent two books building into a good guy we liked, and now – let's see him from the other side, and because hopefully we all want Rebus back we don't want Fox to succeed, therefore he has to be the bad guy. I really liked doing that, a lot of fun."

It wasn't until the eighth Rebus novel, Black and Blue, I remember through some sweetly melting venison stew from that Friday's specials board, that the character – and Rankin – really took off; had he taken a while to like, or to properly "get", his creation?

"Absolutely. The first Rebus just sold a few hundred copies! I don't think I knew Rebus at all then. It was meant to be a one-off; he was just the means of telling a story – no, I probably didn't know or like him enough at the very beginning. It was my editor who said, I liked that guy, you should use him again.

"So he grew, and I grew to know him. I suppose I knew he does have some of the tropes – I prefer that word to cliches – bit of a drinker, bit of a loner, but I also had a believable city, a great city to write about, and one which keeps changing."

He's gazing slowly around a bleakening afternoon, musing on this adopted city of his, in which he still feels occasionally like an outsider despite 20 years and more away from Fife, and remembering his first book contract, signed about half a mile away, for £300. "Edinburgh and Rebus, the mix, allows me to explore that Jekyll and Hyde thing – that whole story began here in Edinburgh, with Deacon Brodie [a respected 18th-century tradesman who was a burglar by night] – of differences between good and bad, and how they can co-exist. The human dichotomy, very Edinburgh. And explore the big question: why do we do bad things to each other? Chemical imbalance, or greed, or our base instincts, or a crucial inability to empathise – all these complex reasons why crime continues. And in all I've looked at it I still find much unresolved. I can point to an evil act, but it's very, very hard to point to someone and say: that is an irredeemably evil human being. So we go back to legend and myth, and call them monsters. It's too horrifying to think they are cut from anything like the same stuff we are."

Strong coffees arrive, and glorious petit fours, and we've already settled much of the independence debate, at least as much as two Scots (even on the same side) ever can without a full 400-year chat; essentially, as someone who's lived in France and London for years, he "still couldn't feel more Scottish wherever I was, or whatever happens here".

The 2014 outcome will depend, he rightly says, on the "head vs heart" of modern politics here, and how many bravehearts swither at the last minute thanks to economic nagging. We've also debated exaggerations of the death of the book, and left mutually unresolved the more tangled one: jazz, rock and folk music, 1975-1990, Tayside vs Fife? And he has reluctantly to scoot, which is a shame, because it's the kind of day, the kind of place, the kind of companion, where you want afternoons to run to 10pm. "It's not a bad life," he considers. "I am, of course, a frustrated rock star – I'd much rather be a rock star than a writer. Or own a record shop. Still, it's not a bad life, is it? You just sit at a computer and make stuff up. As long as you've got an active imagination, which all children have got. I still think most writers are just kids who refuse to grow up. We're still playing imaginary games, with our imaginary friends … That's why I can't, wouldn't, teach creative writing. I don't ever want to know how it works. I want it, forever, to be a mystery. And just thank God that, somehow, when it works, it does work." Standing in Another Man's Grave (Orion) is out now